adding spindle axis to the etch servo config

I am current building a cnc lathe controlled via the etch servo configuration since I am using brushed dc servo motors.
I wanted to add a single channel spindle encoder to do some threads. the spindle speed won't be controlled via the software. I tried adding a third Z axis and configuring its encoder to counter mode and the axis as an angular wrapped rotary axis. the counter mode seemed to work but the wrapped_rotary option didn't. so this method didn't work for me.
what other way can this be done? did I make any mistake in how I tried to achieve the spindle axis?

the encoder is based on an optical sensor and a slot wheel it has a single output. I was planning to use the missing teeth indexing scheme.
how can I setup the encoder to be a spindle encoder? what do I need to modify in the ini/hal files?

the encoder is based on an optical sensor and a slot wheel it has a single output. I was planning to use the missing teeth indexing scheme.
how can I setup the encoder to be a spindle encoder? what do I need to modify in the ini/hal files?

linuxcnc.org/docs/2.9/html/man/man9/moti....html#SPINDLE%20PINS

I think at minimum these pins must be used for spindle sync.
spindle.0.revs
spindle.0.speed-in
spindle.0.at speed (at least set true)
spindle.0.index-enable

You only need to control the spindle if you are trying to rigid tap.

This shows one way to do it (just as an overview ) - your hardware could be different.
linuxcnc.org/docs/2.9/html/examples/spin...ml#_spindle_feedback

If that is not enough info then please post your config files.